Isomerization of light hydrocarbons



April 18, 1950 B. H. sHoEMAKER ET AL.

ISOMERIZATION `0F LIGHT HYDRocARBoNs Filed April 5o, 1945 Patented Apr. 18, 1950 ISOM'ERIZATIN @F LIGHT HYDROCARBONS Bernard H. Shoemaker, Hammond, Ind., and Bernard L. Evening, Chicago, Ill.,v assignors to Standard Gil Company, Chicago, Ill.,- a corporation of Indiana Application April 30, 1943, Serial No. 485,156

sider-able amounts of cracking, disproportiona-A` ticn or other side-'reactions so that the conversion of a narrow boiling range charging stock has resulted in a relatively Wide boiling range product. Oneffexample ofA` the disproportionation reaction isz 2C'5Ill12'- C@Hic-t06H14.y An object of our invention iste direct the hydrocarbon lconversions primarily toward isomerizationand to avoid such sidereactions as the cracking of charging stock to lovv molecular weight hydrocarbons or the convers-ion of charging stock-into higher molecular weight hydrocarbons. A further object is to prolong catalyst activity and catalyst life or, in

vother Words, to produce a larger yield of desirable isomerization products per pound of catalyst material than has heretofore been possible. Another objectis to provide an improved system for isomerizing hydrocarbons with hydrogen fluoride. Other objects will beV apparent as the detailed description of the invention proceeds.

In practicingour `inventionvve may for example isomeriae. normalpentane toy isopentane by contactingxnormal pentane vvithr approximately an equal arnount'of hydrogen fluoride at a temperature' of about 350: tof 400 F, and a pressure of about 1500 tof2500 pounds per 'square inch with intimate contacting in the presence of a small amount of cracking inhibitor. A preferred example of such cracking inhibitor is a cyclic hydrocarbon such as an aromatic or naphthenic hydrocarbon. Generally aromatics are employed in amountsv of about .05 to 3% by volume based on pentane charged. Naphthenes should be employed in larger quantities, i. e., Within the approximate range of .5 to by volume base on charge; in other Words about .5 to 15% by a volume of naphthenes is the equivalent of .05 to 3% by volume of Aaromatics, a unit volume of aromatics being equivalent to about 5 to 10- unit volumes oi'naphthenes as cracking inhibitors in our process. The isomerizaton may also be effected under hydrogen pressure. The invention Yis not limited to pentane nor to these-'pamd ticularf conditions but Will be more fully understood as the following detailed description proceeds.

The accompanying drawing which forms a part olf-this specification is a schematic flow diagram of acommercial plant for isomerizing pentane with hydrogen fluoride in the presence 0f a small amount of a cyclic hydrocarbon cracking inhibitor.

The charging stock for our process is preferably a; saturated C5 hydrocarbon rich in normal pentane although a saturated light naphtha may be employed if it is substantially free from olens. Generally speaking, we may use any saturated hydrocarbons from butane to heptane in boiling range and any mixtures thereof, a fraction from natural. gas being highly advantageous. Hydrocarbons synthetically producedl by ycarbon monoxide-hydrogen synthesis or the hydrogenation vof carbonaceous materials are likewise highly advantageous` provided they are suitably treated for the saturation of' olens or the removal thereof.

Virgin light naphtha fractions having end points up to F. or 200 F. are available in mostA refineries and may be used per se as our charging stock or may be further fractionated and one orv more fractions thereof employed las charging stock.

The catalyst employed in our process is either hydrogen fluoride per se or a hydro-gen fluoride composition. Hydrogen fluoride is only slightly miscible with` hydrocarbons at room tempera-ture;

has aboiling point of about 67 F., a melting point of 117 F., a critical temperaturel of about 446 F;, and a speciiic gravity of about 1.0 at 329 F. sol that it may be readilyseparated from hydrocarbons'rbydistillation, stratification and other commercial. separation means. At lovv temperatures hydrogeny fluoride tends to polymerize and its formula may range from (H506 at low tem'- peratures to HF at high temperatures.

irong nickel',- cobalt; zirconium, etc.

Thevr average molecular weight of hydrogen fluoride Amont-standingy advantage of hydrogen" Along with hydrogen` fluoride per se We Generally speaking, the weight ratio of hydrogen iiuoride catalyst to charging stock in the reaction zone may range from about 0.2511 to :1 and it is preferably in the approximate range of 1:1 to 2:1 or more. The conversion temperature is usually within the approximate range of 150 F. to 500 F. or higher and, for example, may be about 300 F. to 400 F. Higher temperatures may be employed with decreased conta-ct times and vice versa. The weight space velocity in the reaction zone may vary through a considerable range but it is preferably in the approximate range of about .05 to 5, e. g., about .5 pound of charging stock per hour per pound of catalyst in the conversion zone. The pressure in the con version zone is preferably sufficient to maintain liquid or at least dense phase conversion conditions and may be within the approximate range of about 100 to 3000 pounds per square inch,

In order to direct the conversion of pentane or other C4 to Cv saturated hydrocarbons toward true isomerization and to avoid unduly large 4 pressure may be still more essential and it shoul be of the order of 500 to 3000 pounds per square inch. When optimum hydrogen pressures are employed in the conversion it is not so essential that the charging stock contain the critically deiined percentages of aromatics or naphthenes but for best results, particularly in the case of heptanes and hexanes, we employ both the critically dened amounts of aromatics or naphthenes and the stated hydrogen partial pressures.

Our invention is strikingly demonstrated by the following series of experimental runs made on normal pentane with hydrogen fluoride as the catalyst in the absence of added hydrogen and both with and without benzol as an inhibitor for undesired side reactions. In these runs a bomb was employed as the reactor, and it was provided with means for securing the required amount of agitation on intimate mixing. The

f amounts of catalyst and inhibitor used, the conversion conditions, and the results obtained are set forth in the following table:

A B C D E F G Materials:

larts n-pentano (by vol.) 100 100 100 100 100 100 100 Parts HF (by Volume) 21. 5 2l. 5 100 100 100 100 26 Parts HF (by weight) 34 34 158 158 158 158 41 Parts benzol (per cent by vol.) 0. 2 1.0 0. 7 Conditions:

Temperature (F.) 330 375 375 330 330 400 400 Pressure (p. S. 1.). 980 1, 850 2, 600 1, 100 1, 100 2, 200 2, 100 Time (hours) 3 3 3 3 3 3 Products:

C4 hydrocarbons (wt. per

cent) l 29 23 3. 5 Isopentane (Wt. per cent). 5 24 28 16.0 30 Normal pentane (Wt. per e cent 100 94 20 20 77. U 70 100 C@ and heavier (wt. per

cent) 27 20 3. 5

amounts of disproportionation, cracking and other side reactions we employ with a paraiinic charging stock an amount of aromatics in the approximate range of 0.05 to 3% or naphthenes within the approximate range of .5 to Hexanes require more added cyclic hydrocarbons than pentane and pentane requires more than butane; as much as 5% benzol may be required for hexane while as little as 0.01% may be sufficient for butane. In general, in isomerizing paralnic hydrocarbons such as those boiling in the butane to heptane boiling range, we may use an amount of aromatic hydrocarbon ranging from about 0.05 to about 5 percent by weight. When both aromatics and naphthenes are used the amounts of each may be correspondingly reduced, one part of aromatic being equivalent to 5 or 10 parts of naphthenes.

In the case of pentane, hexanes or heptanes, we may effect the conversion in the presence of added hydrogen. The necessary amount and partial pressure of the added hydrogen is likewise dependent upon the particular charging stock. With butanes and pentanes the hydrogen may be entirely dispensed with provided that the proportion of aromatics or naphthenes in the charging stock is within the critical range hereinabove set forth. With a pentane charge somewhat improved results may be obtained by relatively low hydrogen partial pressures, i. e., partial pressures of the order of to 500 pounds per square inch at conversion temperatures of the order of 150 F. to 400 F. With hexanes the addition of hydrogen may be more essential and the hydrogen partial pressure should be within the approximate range of 250 to 1000 pounds per square inch. With heptane the hydrogen partial Run A shows that no conversion is obtained with as little as about one-third part by weight or one-fifth part by Volume (based on charge) of hydrogen fluoride at 330 F. Run B shows that when the temperature is increased to 375 F. with the consequent increase in pressure for maintaining liquid or at least dense phase conditions, a small amount of conversion is obtained, but there is about one part by weight of C4 hydrocarbons formed for ve parts by weight of isopentane. Run C shows that at 375 F. a substantial amount of conversion is obtained when the amount of catalyst is increased to about 1.5 parts by Weight or equal parts by Volume based on charge; this run also shows that the conversion is chiefly disproportionation, the amount of lighter and heavier conversion products far exceeding the amount of isopentane produced. Run D shows that disproportionation is likewise obtained at 330 F. when approximately 1.5 parts by weight of hydrogen fluoride isemployed as compared with the one-third part by weight in Run A.

Run E is substantially identical with Run D except that about .2 part by volume of benzol is added to pentane charging stock. This small amount of added benzol is shown to have the remarkable and unexpected eiect of inhibiting cracking and disproportionation. The butane production dropped from 23 to 3.5% by weight and the amount of Cs and heavier hydrocarbons likewise dropped from about 20% to 3.5%. Without the small amount of aromatic inhibitor (i. e., in Run D), the disproportionation products, C4 hydrocarbons-l-Ce and heavier, amounted to almost twice the total isopentane production. In the presence of only 0.2% of benzene, the amount of isomerization product, isopentane,

Wasi more; than. :tw-ida the. combined .amountstof--.

Cil-hydrocarbons@ and .Ce andnheavier. hydrccao. bons.

Run-E was at. atemperatureoi .400? and withA 1.0.% byevoluinefof.4 added. benaeneiin, .the .pen.tane.. The higher conversion..` temperature4 acted normal `pentane .and retreating, the `latter in multi-stage or. continuous processes, it should thus be possible to convert normal pentanealmostquantitatively. into isopentane.

Run G brings out quite strikingly, the fact thatwhen hydrogen riool-ide yper se is. employed as 'the catalyst,A the concentration thereof in the reactionaone should be substantial.' likeV Run F, was at 400' F.. and in Run G about 0.7"part by; Volume of benzol was employed tor.,

inhibitingv cracking.. and disproportionation. Since asmall -amount of conversion was obtained in Bun.. B. with a somewhat smaller amountof catalyst and a somewhat lower temperature, it would naturally be, expectedthat .at least an' equal amount .of conversion wouldbe effected' at .400 F. The 0.7 per .cent by. volume ofA benzol'inRun (31.,.evidently` inhibited not only the cracking and ,disproportionation,.bnt likewise inhibited isomerization itself since in this run there f' was no rappreciable conversion. The failureto obtain any conversion in Run G' was apparently dueto the fact that lthe concentran tionof hydrogen fluoride was too'low.

The aboverunsf'clearly bring out' the fact that with' hydrogenfluoride as a catalyst, there must be asubstantial an'lountl of catalyst present to ei'ectany conversion. At least about 1 to 2 parts by weight of hydrogen4 fluoride should be upwards' 4of i about 3 f may "retard-fthe desired isomerization reaction i'tselff We" therefore 'errr-A` ployaromatics within' approximate ranger of about 0.05 to 3, preferably about 0.1 to 1.007%.' Excellent conversions are obtained at temperaturesof-the ordery of" to .'400if butllower or highs-rfi'tempcreatures` may," ofi" course, bec'em: ployed':

While the aboveruns'were made ihremv actorsf, it shouldbe` understood?E that we yconter-nplate' Ythe use fof continuous1v 'reactors `'eithery of` the agitator type; the` circulator-rnirrerl` type; or the itower type.Y Likewise;V while r theffabove 'runsz' were@ made on normal pentane; our f inventionvl is Lal'so applicable fto= the conversion`A off-normal'f' butano 'to isobutane, normal henanefand methyl pentanesv to dimethyl butanes,v etc.-

An example fof-1' a" con'lrrierciali` f applicationf oilourr'iuvention for the -isomerizatonfv off normal pentane is illustrated` 'in` Ithedrawing and *from* the#l f following` detailed f descnifptiorrl 1 thereof.. 1 A pentane charging stock-containingboth? normar and-.isopentane ist introduced. :through it to isopentane tower.v ii which .may ,baopera-ted at a -pressurooi about. pounds .gaugef.withP a top.,

temperature, of.-` about .140?. and abottorn..temV perature. .ci about 16.0 E...the..bottomutemperav turebeing obtained 'by the. use of..a.suitablere-v Even small" boiler" or rehea-ter.- vdiagrarnnlaticall'yvv illustrated? Isopentane lighter components by; coil; f tta.

are-f taken;v overhead. Normalpentanev and heavier Vcomponents are-withdraWn through line.`

@hand introduced .by-pump Nieto reruntower iiiv-w-hich may bewoperatedtat about-25poundsf gauge pressure with a tcp. temperature of" about 15.9 E'. and a.bottoniftemperature'of 4about 205- .F.suitable reboilerbeing employed as: diagrammatical'ly. `illustrated.by coil. Products-'heavier thanonormar pentane are :withdrawn through-1 line. H..

reactor 25. About 1/2 rbarrel of: benzene isf-intro-y duced. into.. line 23. from.' source 215 rby' pum-p- 21 for each 190 barrels of pentane which is charged to the. reactor.

Thereactor itself. mayv beni varioustypesfde-` pending somewhat.uponv they conditions.- under.: which itis opera-ted,V Itmay. iorzexample, bev a reactor. of the .typefemployedfor .sulfuric acid alkyl-ation. as exempliiied by.` the:` contactor der` scribed in U. S. Patent 2,238,302@v A circulator or agitator in thereactornaay bedrivenby motor 28... Under somefconditions o operationa. simple tower type reactorY may` be. -employed-andf the hydrOCarbOnsmaypaSs .upwardly or downwardly depending on relativedensity through aloolumnoiliduid rif/'drogen fluoride..v In. this particularV example, however, amechanical. agitatoror` cir oulator'is. employedso that relative-densities ofl liquid, hydrogen..luoride and hydrocarbons` arev of no particular consequence.. the. reactor` may be. maintained at` aitemperature.

of. about. 400 and.y afpressure ot .about -220dpounds lper square. inch.. The actualtinieof. con

tact of the pentane. in. theftower may be` ofA theU order ot about Lto Bhours.- The tower may .con.

tain .about 1 .to 2. volumes of .hydrogenuoride/ for eachvolume or".hydrocarbon.,

TheY product stream-may be continuously re moved through lines 29 and 30 to' a .high=tem perature separator 3l.. Separated hyd-rogerrfluk oride. may be returnedtorthevreactor through line 32 andthe` remaining.` product stream may be: passed. through. line 33, line.34,. cooler 35Vand, valve. Stato settlingW chamber .31u/bieb may be atV substantially atmospheric temperature, i. e., about F. or lower and either .at substantially` conversion pressure. or at.-.somewhat .reduced pressurer the hydrogen fluorideseparates..outas .aliquid and isreturned ,through line..38 bypump. 39.to..

reactor .2.5. The. .remaining product stream. .then

Apasses through line 40 and pressure .reducing valve. al to. azeotropic distillationstill 4,2 .which acts4 as. a hydrogenuoride. stripper. This still.

may be .providedwith 4a.,suitable-heating or re..l boiler means .43 .at itsbase andit mayv be.;oper-A ated at. pressures of. the order of 25. to 250, pounds.`

per square inch., Thisl tower or. still' 42.1sso opere ated that azeotropes are, formed. with ,low boiling hydrocarbons, such as. l butano.. and. these'. azeov.

tropes vare taken- .overhead..through.line. and. cooler '55 toseparatorli whichmay;operateat about. atmospheric. temperaturad. e... at. tem

peratures readily obtainable by. available. con:

denser. water. The condensed liquid separates.. into a heavy hydroluoric acid layer which is..-

withdrawnthrough 1ine41 and returned by, pump,

In this example-v At. the` low temperature the....b.u11-:. ofv4 48 to reactor 25. The upper hydrocarbon layer flows over weir 49 and is returned through line 50 by pump 5| to the top of the azeotropic still 42. Any methane or other uncondensed gases may be vented from the top of the settler or reflux accumulator 46 either continuously or from time to time through line 52.

The liquid product together with butanes in excess of those required for azeotropic formation are withdrawn from the base of azeotropic still 42 through line 53 and are contacted in treating system 54 with bauxite at elevated temperatures or with other known contacting or treating agent for removing alkyl iiuorides and preventing any hydrogen iluoride from reaching or being formed in the product fractionation system. The prod uct thus freed from hydrogen fluoride and alkyl luorides is returned from treating system 54 by line 55 to a point in isopentane tower Il which is preferably above the point of charging stock inlet l0.

Any unisornerized pentane and higher boiling hydrocarbons pass downwardly in tower Il and thence to rerun tower l from the top of which the isomerization charge is obtained. Any small amount of higher boiling hydrocarbons which may be formed during the isomerization is withdrawn through line I l.

The overhead from tower I! will contain the isopentane from the original charge together with isopentane from the product stream and any small amount of butanes that may be present in the original charge or in the product stream. The overhead from tower Il passes through line 56 and condenser 5l to accumulator 58. A part of the accumulated liquid is returned by 'pump 59 and line 00 for reux in the top of tower Il. The remainder of the liquid from the accumulator is introduced by pump BI and line 62 to debutanizer tower 63 which may operate at a pressure of about 100 pounds gauge with a top temperature of about 143 F. and a bottom temperature of about 224 F., a suitable reboiler being employed as diagrammatically illustrated by coils 6d.. The isonentane product stream is removed from the base of the debutanizer tower through line 55.

Hydrocarbons lighter than isopentane are taken overhead from the ton of tower 53 through line 65 and cooler El to accumulator 58. If necessary or desirable, gases may be vented from the top of this accumulator through line 59. The accumulated liquid is removed by nump 10, a part being returned by line ll to serve as reflux in the top of tower 53 and the remainder being withdrawn a butane stream through line 12.

Makeup hydrogen iluorlde may be introduced directly into the reactor through line 'i3 but is preferably introduced to the inlet of pump 08 through line 13a.

When a tower type of reactor is employed or where there is not a large carryover of hydrogen fluoride with the product leaving reactor through line 20, the high temperature separator 3l may be dispensed with and the product stream may be simply by-nassed through line l. Various other modiiicatons and alternative arrangements of the system may be apparent from the above description to those skilled in the art, Those skilled in the art will. of course. recognize the precautions that should be taken in handling hydrogen fluoride and with the proper precautions this reagent may be employed without undue hazards to the operators. In order to avoid corrosion difficulties the charging stock should,

of course, be substantially anhydrous and provision should be made throughout the system for preventing the entrance of any moisture. No invention is claimed in any of these expedients per se and no detailed description thereof appears to be necessary.

As a further example of our process we may isomerize normal hexane or methyl pentane for the production of dimethyl butane by first preparing a charging stock rich in normal hexane or methyl pentane and containing about .1 to 5% of aromatics or about .5 to 25% of naphthenes or both. This charging stock may then be intimately admixed with about 25 to 500% or more by weight` e. g. 150% by weight of hydrogen fluoride and contacted in a reaction zone at a weight space velocity of about .05 to 5, e. g., .5 pound of charging stock per hour per pound of catalyst in the reactor. The temperature of the reactor may be within the approximate range of about 250 to 500 e. g. about 400 F. The total reaction pressure may be of the order of 1000 to 4000 pounds per square inch, e. g. about 2500 pounds per square inch and the hydrogen partial pressure may be of the order of 250 to 1000, e. g., about 500 pounds per square inch. Here again both the use of the hydrogen pressure and the use of the critically dei-ined amounts of aromatics or naphthenes tends to direct the conversion toward isomerization and to suppress undesirable cracking and disnroportionation. The conjoint use of both inhibitors should give optimum results.

Examples of aromatic inhibitors which may be employed in the practice of our invention include benzene, toluene, xylenes, other alkyl benzenes, naphthalenes, etc. Examples of naphthenes include: cyclopentane, methyl cyclopentanes, cyclohexane, methyl cyclohexane, dimethyl cyclohexane, etc. We prefer as cracking inhibitors aromatics and naphthenes containing six carbon atoms although others may be used with good results.

While we have described in detail specific examples of our invention it should be understood that the invention is not limited to such examples nor to the conditions dened in connection therewith since modications and alternate ol?- erations and operating conditions will be apparent from the above description to those skilled in the art.

We claim:

l. The isomerization process which comprises contacting a charging stock consisting essentially of liquid normal pentane with a catalyst consisting essentially of liquid, substantially anhydrous hydrogen fluoride in a conversion zone at a temperature between about 300 and about 400 F. under a pressure sufficient to maintain substantially liquid phase conversion conditions, maintaining an amount by weight of hydrogen fluoride in the conversion zone which is at least equal to the amount by weight of normal pentane therein, and effecting the conversion. in said sone in the presence of between about 0.05 and about 3% by volume of an admixed aromatic hydrocarbon based on the normal pentane.

2. The process of claim 1 wherein the admixed aromatic hydrocarbon is benzene.

3. The method of isomerizing a normally liquid parailinic hydrocarbon boiling within the boiling range of gasoline which comprises contacting said hydrocarbon in the liquid phase with at least an equal weight of a catalyst consisting essentially of liquid, substantially anhydrous hydrogen uof'ide at a temperature between about 1501'F.- and -1 about V500" F. under a-pressure suiiicient `to maintain vthe materials being-contacted in the liquid phase, said-pressure beingbetweenabout 100 vand about 30Go-p. s; i., for a -period of time sufficient comprises contacting the :samewith atleast an l equal weight of liquid, substantially. anhydrous hydrogen vfluoride in lthe presence of between about 0.05 and" about '-3 per cent by yolumelof an admixed aromatic hydrocarbon, A'basedon -hexvaries, at a temperature between about 150 li". and A about y500" F. under a--pressure sufficient tovmaintain the materials being contacted in the liquid phase, said pressure -being- 'between about 100 and about 3000 p. s. i., said ,contacting being effected inthe presence of hydrogen in an amount suii-w cient to produce la-hydrogen partial-pressure between about250 andi-about 1000 p. s. i.

6. The method of `-isorneriaing heptanes which comprises contacting `rthe same with at least' an equal weight lofliquid, substantially anhydrouss;

hydrogen fluoride-in `the presence ofbetween about 0:05 and about 3 per cent by volume ofan adm-ixed aromatic hydrocarbon, based on hep- ;tanes, at a temperature between aboutv 150F.

andabout 500D F. under apressure vsufiicient to l ymaintain the materials being contacted in the liquid phase, vsaid pressure being between about 100 and about 3000` p. s. i., said contacting being effected in the presence of hydrogen in an amount sufficient to producea hydrogenpartial pressure between about 500 and about 3000 p. s. i.

7. A process rfor eifecting the isomeriZa-tion vof anisomerizable normallyliquid paraffin hydrocarbon boiling within the boiling range of` gasoline while inhibiting cracking conversion which forms paraflin hydrocarbons of lower and higher molecular weights, Awhichgprocess comprises admixing Vwith said paraffin `hydrocarbon a low boiling aromatic hydrocarbon in aV small Yproportion suiiicient substantially to inhibit said crack- -ing conversionbut insuiiicient substantially to inhibit said isomerization reaction,contacting the resultant mixture under isomerzation reaction conditions with at least about an equal weight of a catalyst consisting essentially of iliquid, sub- F Vstantially anhydrous hydrogen uoride, and recovering from the effluents got saidisomerization reaction a hydrocarbon fractioncontaining an isomeric paraffin so produced.

8. A process forxeffecting the isomerization of -an isomerizable normallyjliquid paraiiin hydrocarbon boiling within the boiling rangeof gasoline whileinhibiting ,cracking conversion which forms paraiin hydrocarbons. oilower and higher Amolecular weights, which processcomprises ,ad-

mixing with said paraiiin hydrocarbona low boiling aromatic hydrocarbon in anamount with- ,a catalyst consisting essentially of 1iquid,.sub kstantially ranhydrous hydrogen fluoride,v and frecoverng Vfrom theeiiluents ofsaid isomerization reaction -a hydrocarbon fraction containing san isomeric paraffin so produced.

9. A process ffor effectingltheisomerization of an isomerizable nnormally iiquidv paraffin hydrocarbon boiling within the boiling ,range Aof -gasolinev while inhibiting crac-king vconversion which forms paraffin yhydrocarbons -of lower-and .higher molecular weghts,-which process comprisesfa'dmixing with saidfparaiin"hydrocarbon-an `aro matic hydrocarbon-in a smal-l proportionsuflivcient substantiallylto `inhibit said `cracking conversion-but insufiicient substantially to inhibit said isomerization =reaction,-contacting 'the-1resultant mixture under isomerization .reaction yconditions with at Aieast rabout-an -equal -weigl-it of Ha catalyst consisti-ngessentially -of 7liquid, substantially anhydrous hydrogen iii-ioridefand-recovering from the `eiiiuents of'said isomerization-'re- `action a hydrocarbon fraction 4containing --an isomeric paraffin so produced.

1,0. AA Iprocess for effecting the isomerizati'on of --an Visoinerizable normally liquid paraiiin hydrocarbon boiling withinthe boiling range off/gasoline while inhibitingpracking conversion which forms paraifin hydrocarbons of --lower and higher molecular weights, which process comprises `Aad- -1niXingwith said paraiiin hydrocarbon selected -irom the'group consisting of aromatic `hydrocarbons -and 1 naphtheni-c hydrocarbons in -a small lproportion v'suilcient-'substantially 'to inhibit said 4cracking conversion but insufficient substantially to-inhibit said isomerization reaction, contacting the resultant mixture Vunder isomerization reaction conditions with "at least about an equal weight of acatalyst consisting essentially of liquid,A substantially 'anhydrous-hydrogen fluoride, and recovering frornthe efiluentsi of said isomerization 'reactionffa hydrocarbon fraction containing an isomeric-parain uso produced.

11. A process for eiectingf the isomerizationof an isomerizablenormallyvliquid parain `hydrocarbon boiling -within the boiling range of `gasolline while inhibiting cracking conversion'which forms paraiiinhydrocarbons of lower and `higher "molecular weights, lwhich'process comprises adi naphthenichydrocarbons ina small proportion sufficient substantiallyy to linhibit .said v:cracking conversion but insuficient `substantially -`to inhibit said isomerization reaction,-- contacting the resultant mixtureunder isomerization reaction conditions withfatgleast uabout an equal `weight of .a catalyst consisting essentially-"of liquid, substantially anhydrous hydrogen fiiuoride, Aand recovering `from the-effluents of said lisomer-ization yreaction a hydrocarbon fraction containing an isomeric l,paraiiin so produced.

l12. A process yfor "effecting theisomerizationfof an isomerizable r'normally liquid lparaiiin hydro-- vcarbonboiling within'the boiling rangeofgasoline .while inhibiting l vcracking lconversion which forms paraffin hydrocarbons` of lower and higher molecular weights, which comprises admixing with said parain-hydrocarbon a cyclic hydrocarbon lselected from `the group consistingpf aromatic hydrocarbons and `naphthenic hydrocarbons in a :small proportion suiiicient-substantially to inhibitssaid cracking yconversionbut with at least about an equal lweightof a catalyst consisting essentiallyA of liquid, substantially anhydrous hydrogen fluoride at a temperature between about 150 F. and about 500 F. under a pressure sucient to maintain the materials being contacted in the liquid phase, for a period of time suiilcient to effect substantial isomerization of said paraiin hydrocarbon, and recovering from the efuents of said isomerization reaction a hydrocarbon fraction containing an isomeric paraflin so produced.

13. A process for effecting the isomerization of an isomerizable normally liquid para'in hydrocarbon boiling within the boiling range of gasoline while inhibiting cracking conversion which forms parain hydrocarbons of lower and higher molecular weights, which process comprises admixing with said parailin hydrocarbon a low boiling cyclic hydrocarbon selected from the group consisting of aromatic hydrocarbons and naphthenic hydrocarbons in a small proportion sufflcient substantially to inhibit said cracking conversion but insufficient substantially to inhibit said isomerization reaction, contacting the resultant mixture with at least about an equal Weight of a catalyst consisting essentially of liquid, substantially anhydrous hydrogen uoride at a temperature between about 300 F. and about l00J F. under a pressure suliicient to maintain the materials being contacted in the liquid phase, for a period of time suicient to effect substantial isomerization of said paraffin hydrocarbon, and recovering from the effluents of said isomerization reaction a hydrocarbon fraction containing an isomeric paraflin so produced.

14. The process of claim 7 wherein the aromatic hydrocarbon is benzene.

15. A process for effecting the isomerization of an isomerizable normally liquid paraiiin hydrocarbon boiling within the boiling range of gasoline while inhibiting cracking conversion which forms paraffin hydrocarbons of lower and higher molecular weights, which process comprises admixing with said parain hydrocarbon a naphthenic hydrocarbon in a small proportion sufficient substantially to inhibit said cracking conversion but insucient substantially to inhibit said isomerization reaction, contacting the resultant mixture under isomerization reaction conditions with at least about an equal weight of a catalyst consisting essentially of liquid, substantially anhydrous hydrogen uoride, and recovering rom the eflluents of said isomerization reaction a hydrocarbon fraction containing an isomeric parain so produced.V

16. A process for eiiecting the isomerization of an isomerizable normally liquid paraffin hydrocarbon boiling within the boiling range of gasoline while inhibiting cracking conversion which forms paraiin hydrocarbons of lower and higher molecular weights, which process comprises admixing with said paraffin hydrocarbon a low boiling naphthenic hydrocarbon in a small proportion suiiicient substantially to inhibit said cracking conversion but insufficient substantially to inhibit said isomerization reaction, contacting the resultant mixture under isomerization reaction conditions with at least about an equal weight of a catalyst consisting essentially of liquid, substantially anhydrous hydrogen fluoride, and recovering from the eiuents of said isomerization reaction a hydrocarbon fraction .containing an isomeric paraiin so produced.

17. A process for effecting the isomerization of an isomerizable normally liquid lparaffin hydrocarbon boiling within the boiling range of gasolineY while inhibiting cracking conversion which forms parain hydrocarbons of lower and higher molecular weights, which process comprises admixing with said parafn hydrocarbon a low boiling naphthenic hydrocarbon in a small proportion sucient substantially torinhibit said cracking conversion but insufficient substantially to inhibit said isomerization reaction, contacting resultant mixture with at least about an equal weight of a catalyst consisting essentially of liquid, substantially anhydrous hydrogen fluoride at a temperature between about 300 F. and about 400 F. under a pressure sufficient to maintain the materials being contacted in the liquid phase, for a period of time suflicient to effect substantial isomerization of said parain hydrocarbon, and recovering from the effluents of said isomerization reaction a hydrocarbon fraction containing an isomeric parain so produced.

18. A process for effecting the isomerization of an isomerizable normally liquid paraiiin hydrocarbon boiling within the boiling range of gasoline while inhibiting cracking conversion which forms paraffin hydrocarbons of lower and higher molecular weights, which process comprises admixing cyclohexane with said paraffin hydrocarbon in a small proportion sufficient substantially to inhibit said cracking conversion but insufficient substantially to inhibit said isomerization reaction, said proportion being between about 0.5 and about 15% by Volume, based on said paraflin hydrocarbon, contacting the resultant mixture with at least about an equal weight of a catalyst consisting essentially of liquid, substantially anhydrous hydrogen iiuoride at a temperature between about F. and about 500 F. under a pressure sufiicient to maintain the materials being contacted in the liquid phase, for a period of time sufficient to effect substantial isomerization of said parain hydrocarbon, and recovering from the eliluents of said isomerization reaction a hydrocarbon fraction containing an isomeric parain so produced.

19. A process for eiecting the isomerization of an isomerizable normally liquid paraffin hydrocarbon boiling within the boiling range of gasoline while inhibiting cracking conversion which forms paraiiin hydrocarbons of lower and higher molecular weights, which process comprises admiXing a low boiling naphthenic hydrocarbon with said paraffin hydrocarbon in a small proportion suiiicient substantially to inhibit said cracking conversion but insuiiicient substantially to inhibit said isomerization reaction, said proportion being between about 0.5 and about 15% by volume, based on said parain hydrocarbon, contacting the resultant mixture with at least about an equal weight of a catalyst consisting essentially of liquid, substantially anhydrous hydrogen fluoride at a temperature between about 150 F. and about 500 F. under a pressure sufcient to maintain the materials being contacted in the liquid phase, for a period of time sumcient to effect substantial isomerization of said parafn hydrocarbon, and recovering from the eilluents of said isomerization reaction a hydrocarbon fraction containing an isomeric parafn so produced.

20. The process of claim 19 wherein the isomerization reaction temperature is between about 300 F. and about 400 F.

21. A process for effecting the isomerization of normal pentane while inhibiting cracking conversion which forms paraffin hydrocarbons of lower and higher molecular weights, which process 7&5` comprises admixing cyclohexane with said normal pentane in a small proportion suicient substantially to inhibit said cracking conversion but insucient substantially to inhibit said isomer ization reaction, said proportion being between about 0.5 and about 15 percent by volume, based on said normal pentane, contacting the resultant mixture with at least about an equal Weight of a catalyst consisting essentially of liquid substantially anhydrous hydrogen fluoride at a temperature between about 350 F. and about 400 F. under a pressure suiicient to maintain the materials being contacted in the liquid phase, for a period of time sucient to effect substantial isomerization of said normal pentane, and recovering from the eiiiuents of said isomerization reaction a hydrocarbon fraction containing isopentane.

BERNARD I-I. S-HOEMAKER. BERNARD L. EVERING.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 2,260,279 DOuvlie et al Oct. 21, 1941 2,265,870 Schuit Deo. 9, 1941 2,266,012 DOuville et a1. Dec. 16, 1941 10 2,283,142 rpatieff et ai. May 12, 1942 2,288,866 Hoog July 7, 1942 2,299,716 Peski Oct. 20, 1942 2,300,249 Evering et a1 Oct. 27, 1942 2,306,253 McMillan Dec. 22, 1942 15 2,318,226 rpatieff et ai. May 4, 1943 2,324,762 Calhoun et al. July 20, 1943 2,337,419 Sensel Dec. 21, 1943 2,344,890 Whiteley Mar. 21, 1944 2,350,834 Sensei et a1 June 6, 1944 20 2,355,198 Atwell Aug. 8, 1944 2,376,078 Oberfell et al May 15, 1945` 

13. A PROCESS FOR EFFECTING THE ISOMERIZATION OF AN ISOMERIZABLE NORMALLY LIQUID PARAFFIN HYDROCARBON BOILING WITHIN THE BOILING RANGE OF GASOLINE WHILE INHIBITING CRACKING CONVERSION WHICH FORMS PARAFFIN HYDROCARBONS OF LOWER AND HIGHER MOLECULAR WEIGHTS, WHICH PROCESS COMPRISES ADMIXING WITH SAID PARAFFIN HYDROCARBON A LOW BOILING CYCLIC HYDROCARBON SELECTED FROM THE GROUP CONSISTING OF AROMATIC HYDROCARBONS AND NAPHTHENIC HYDROCARBONS IN A SMALL PROPORTION SUFFICIENT SUBSTANTIALLY TO INHIBIT SAID CRACKING CONVERSION BUT INSUFFICIENT SUBSTANTIALLY TO INHIBIT SAID ISOMERIZATION REACTION, CONTACTING THE RESULTANT MIXTURE WITH AT LEAST ABOUT AN EQUAL WEIGHT OF A CATALYST CONSISTING ESSENTIALLY OF LIQUID, SUBSTANTIALLY ANHYDROUS HYDROGEN FLUORIDE AT A TEMPERATURE BETWEEN ABOUT 300*F. AND ABOUT 400*F. UNDER A PRESSURE SUFFICIENT TO MAINTAIN THE MATERIALS BEING CONTACTED IN THE LIQUID PHASE, FOR A PERIOD OF TIME SUFFICIENT TO EFFECT SUBSTANTIAL ISOMERIZATION OF SAID PARAFFIN HYDROCARBON, AND RECOVERING FROM THE EFFLUENTS OF SAID ISOMERIZATION REACTION A HYDROCARBON FRACTION CONTAINING AN ISOMERIC PARAFFIN SO PRODUCED. 